Functional analysis and evaluation of ultrastructure of respiratory cilia in healthy Chinese children in Hong Kong

Abstract

Introduction: Normal reference range of ciliary structure and beat frequency (CBF) is available in Western population but lacking in the Chinese population for the early diagnosis of Primary Ciliary Dyskinesia (PCD). This study aims to establish a reference of the ciliary structure and beat frequency in a healthy Chinese paediatric and adolescent population. Project Objectives: Our objective is to establish the normal reference range for respiratory CBF and determine the ciliary ultrastructure in healthy Chinese children in Hong Kong. Methods: Subjects Nasal epithelial cells were obtained from 162 children (age range 2-17 years) by brushing inferior turbinate. CBF The movement of cilium was examined using a high speed camera. CBF of each ciliated strip was counted and a maximum of 10 ciliated edges were analyzed per subject. CBF was determined by the number of frames required to complete 10 cycles. Ultrastructure Ciliary ultrastructures were examined using transmission electron microcopy. Data analysis: Age were first sub grouped into 2-6, 7-12 and 13-17. The mean for CBF was compared among each age group using ANOVA. Standard deviation, 5th and 95th percentiles, and 95% confidence intervals of whole age group were calculated if there is no significant observed. Results: Nasal brush samples obtained from 141 healthy children (70 male) were included for CBF and CBP evaluation following the inclusion criteria. The mean CBF for children was 10.4Hz (SD 2.2, 95% CI 10.0 to 10.8). There was also no significant difference in mean CBF between the individual age groups (unpaired t-test, p>0.5). For CBP, circulating beating cilia was found on ciliated strips from a child. Normal CBP was observed in the other samples. One hundred and twenty five samples were sufficient for ultrastructural analysis. Dynein arm defects were not found in the cilia. The mean outer and inner arm counts were 8.5 and 7.8 for children. Microtubular defects were found in 9.2% of cilia counts from children. Other ciliary ultrastructural defects were found in less than 3% of cilia for individual age groups. Conclusions: The normal reference range of CBF for children was 10.4Hz (SD 2.2, 95% CI 10.0 to 10.8). A further investigation of microtubular defects will be followed.